The effects of pH on U(VI)/Th(IV) and Ra(II)/Ba(II) adsorption by polystyrene-nano manganese dioxide composites: Fourier Transform Infra-Red spectroscopic analysis.

Fourier Transform Infra-Red (FTIR) spectroscopy provides structural information of prime importance to understand ions coordination to adsorbents. This consequently aids in the design of improved ion exchange materials and help in deriving the optimum adsorption conditions. In the present work, the adsorption mechanism of both U(VI)/Th(IV) and Ra(II)/Ba(II) radionuclides couples onto polystyrene-nano manganese dioxide (PS-NMO) composite is reported in relation to the effect of working solution pH. The separation of each radionuclide couple; i.e. U(VI)/Th(IV) and Ra(II)/Ba(II); could be effectively achieved at pH = 3 and pH = 1 respectively. The pH values not only determine the species of the respected elements that are mainly present in aqueous solution before applying the adsorbent, but it also alters the structure of the composite adsorbent. FTIR spectroscopy showed that Th(IV) formed inner sphere complexes and occupied the A site in the dioxide layer, while U(VI) formed outer sphere complexes on the surface of the composite. Spectra subtraction showed that some aromatic bands and vinyl C-H bands were split or shifted to lower wavenumbers with the loading of Ba(II). This was attributed to changes in the composite stereochemistry to accommodate Ba(II). The working solution pH could be the key in the separation process of both U(VI)/Th(IV) and Ra(II)/Ba(II) from their mixture, and FTIR spectroscopy stands as a useful technique to explain the difference between metal ions responses to adsorbants.

A Styrofoam-nano manganese oxide based composite: Preparation and application for the treatment of wastewater.

Nano-composites were synthesized by the reaction of waste polystyrene (PS) and KMnO4. The structure of the composite was controlled by the solvent/non-solvent system and the concentration of KMnO4. The FTIR spectra indicated the functionalization of PS and the attachment of NMO with the polymer chains. The maximum adsorption capacities (qmax) were 10,000 and 5000 Bq g-1, for U and Th respectively. Different but controllable sorption/desorption behaviours were noted between Th and U, which could be promising in the separation of Th and U from their mixture.

An innovative procedure for NORM scales treatment and radionuclides separation.

The present study focuses on the development of a new chemical treatment method for naturally occurring radioactive materials (NORM) scale wastes from the oil industry. The method consists of three-stages, including the separation of oil using the Fenton oxidation process at room temperature, the complete dissolution of soluble and slightly soluble salts and separation of Ra and Pb isotopes. The proposed method can be considered as an innovative procedure for NORM scales treatment and radionuclides separation, which in turn support the radioactive waste management with economic benefits.

Chemical fractionation of radium-226 in NORM contaminated soil from oilfields.

Contamination of soil with 226Ra is a common problem in the oilfields, leading to costly remediation and disposal programmes. The present study focuses on the chemical fractionation and mobility of 226Ra in contaminated soils collected from an oilfield using a three-step sequential extraction procedure (BCR). The total activity concentrations of 226Ra in contaminated soils were measured and found to be in the range from 1030 ± 90 to 7780 ± 530 Bq kg-1, with a mean activity concentration of 2840 ± 1840 Bq kg-1. The correlation between the total concentration of 226Ra and soil properties, mainly pH, LOI, Corg, clay and Ca, was investigated using the principal component analysis method (PCA). The chemical fractionation of 226Ra was studied using the sequential extraction method (BCR). The highest fraction of 226Ra (27-65%) was found to be in the acid-reducible fraction, which suggests that 226Ra is mainly bound to FeMn oxides. The BCR method showed that high percentages of 226Ra were found to be in mobile soil phases (between 45 and 99%). Consequently, groundwater contamination could occur due to the remobilization of 226Ra from soils under normal environmental conditions. However, the obtained results could be useful to reduce the volume of NORM wastes generated from the oilfields and decision-making process for final treatment and disposal of NORM-contaminated soil.

Dissolution of [²²6Ra]BaSO4 and partial separation of ²²6Ra from radium/barium sulfate: A new treatment method for NORM waste from petroleum industry.

Complete dissolution of [(226)Ra]BaSO4 precipitate was successfully performed using NaNO2 as a reducing agent in acidic solution at room temperature. Results showed a significant effect of acid and NaNO2 concentrations and temperature on the dissolution efficiency. The method was successfully used for separation of radium from NORM scale samples from the petroleum industry; sufficient volume reduction of NORM waste was achieved. The obtained (226)Ra solution was purified using two separation methods. The dissolution method can be of great interest in the development of radiochemical analysis of radium isotopes.